Crystal structures of unusual titanocene by-products from attempted dimerization of terminal alkynes

Structures of unusual organometallic products mu-[(1,2,3,3a, 7a-eta):(3a,4, 5,6,7,7a-eta)-4,7-bis(trimethylsilyl)indenyl]-di-mu -hydridobis(eta (5)-cyc lopentadienyl)titanium(Ti-III/Ti-II) (9) (9) and mu-[(3,4,5-eta):(4,5,6-eta )-(E,E)-2,2,7,-tetramethylocta-3,5-diene]bis{bis(eta (5)-methylcyclopenta-d ienyl)titanium} (10a) were determined by X-ray diffraction analysis. Compou nds 9 and 10a arose as by-products in very low yields in the Ti(C5H5)(2)(et a (2)-Me3SiC=CSiMe3)-HC=CSiMe3 and Ti(C5H4Me)(2)(eta (2)-Me3SiC=CSiMe3)-HC= CCMe3 systems, respectively, when exposed to sunlight. Mechanisms of their formation were tentatively discussed.